Actually, I looked at doing a GP2X version of my last game, a platformer that I released last October on Clickgamer, Pocketgear and Handango but I didn’t get a good frame rate; that's a one level per screen game but did include a lot of clones. The game I’m working on now is a scrolling isometric based game, its still fairly basic at the moment but early tests provided a very, very poor framerate on GP2X
I'm also developing it for PC and Pocket PC (on both its running like a dream), but I'd love to be able to export a playable GP2X version as well.